Electromagnetically actuated camoperated rotary multi-switch relay



Feb. 2, 1965 c. c. ROBERTS ET AL 3,1 8,629 ELECTROMAGNETICALLY ACTUATED CAM-OPERATED ROTARY MULTI-SWITCH RELAY Filed June 16, 1961 5 Sheets-Sheet 1 I a 4'5 93 INVENTORS ATTORNEYS Feb. 2, 1965 c. c. ROBERTS ET AL 3,168,629

ELECTROMAGNETICALLY ACTUATEID CAM-OPERATED ROTARY MULTI-SWITCH RELAY Filed June 16, 1961 5 Sheets-Sheet 2 50 W .56 INVENTORS C///7/5 c: mama, 4$ FR/WC/S lemae mr,

BY S J 5W W 4 M ATTORNEY-6 Feb. 2, 1965 c. c. ROBERTS ET AL 3,168,629 ELECTROMAGNETICALLY ACTUATED CAM-OPERATED ROTARY MULTI-SWITCH RELAY Filed June 16, 196

5 Sheets-Sheet 3 IN VENTOR5 007F455 c. Rosa/W3, fzaqxvcxs A. MOP/7M ATTORNEYS Feb. 2, 1965 c. c. ROBERTS ET AL 3,168,629 ELECTROMAGNETICALLY ACTUATED CAM- ROTARY MULTI-SWITCH RELAY OPERATED Filed June 16. 1961 5 Sheets-Sheet 4 IN VENTOR-S M02455 cdaoamts, sen/v05 A, Ma a/v,

aJaA-u, QWMWJRW ATTORNEYS Feb. 2, 1965 c. c. ROBERTS ET AL 3,168,629

ELECTROMAGNETICALLY ACTUATED CAM-OPERATED R0 LTI TARY MU SWITCH RELAY Filed June 16, 1961 5 Sheets-Sheet 5 INVENTOR6 FILE-.5 C- 055,975,

ATTORNEYS United States Patent Ofifice 3,168,622? ELEQTEGMAGNETECALLY ACTUATED CAM- OFERATED RUTARY l'VULTl-dl VEHIH RELAY Charles C. Roberts, lie. 5, Frederick, Md, and Francis R. Moran, Boliinger Road, Weshninster, Md. Filed .lune 16, 1961, Ser. No. 117,736 tClaims. (Cl. sea-tea) This invention relates to a multi-switch relay device operable to control a plurality of electrical circuits by remote control and contains an electromagnetically operated step-by-step rotary control member for selective or sequential high speed opening and closing of the circuits.

It is an object of this invention to provide in a rotary multi-switch relay device a plural switch means in which the contact opening or closing time interval is of extremely short duration or substantially instantaneous for each of the various circuits when the rotary control member is actuated.

Another object is to provide a rotary plural switch relay device having an improved mode of operation that minimizes arcing between its electrical contacts during opening or closing thereof.

A further object is to provide a sturdy and compact rotary multi-switch relay that operates effectively and reliably at very high speeds of operation in selective or sequential control of a plurality of electric circuits.

further object is to provide an electrical relay having a rotary cam means with lugs thereon operable to con trol a plurality of dual circuits having extremely short contact make and break time intervals.

A further object is to provide an electrical relay for controlling a plurality of circuits where a rotary cam, having spaced radially extending lugs with fiat ends and radial walls disposed at 90 degrees or less to said flat ends to form sharp or substantially sharp peripheral edges, is engageable by a contact-controlling arm likewise having a sharp-edged end to effect an extremely rapid make and break between the circuit-controlling contacts of the relay.

These and other objects of the invention and the advantages that it provides will be apparent from the following description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a side elevation of the relay device showing the circular disposition of the plural circuit contacts and the electromagnetically driven rotary control means therefor;

FIGURE 2 is a plan vi w of the relay device;

FIGURE 3 is a vertical longitudinal section of the relay taken on line 3 -3 in FIGURE 2;

FIGURE 4 is a perspective View of the relay viewed from the right in FIGURE 1;

FIGURE 5 is an enlarged fragmentary view showing a portion of the relay contacts and rotary control means shown in FIGURE 1;

FIGURE 6 is a fragmentary enlarged view showing a modified electrical conductor arrangement of the movable contact arm;

FIGURE 7 is side elevation of a relay similar to the preceding embodiment but showing a modified contact and conductor arrangement for groups of controlled single circuits;

FIGURE 8 is an enlarged fragmentary perspective view of one of the groups of controlled single circuits or" FIGURE 7.

Referring now more particularly to the drawings, the supporting element for the multi-contactor relay comprises a horizontally opening U-shaped frame member 1 of non-magnetic material which forms a housing between its parallelly extending arms 2 and 3 for the coil 4, having position in arcuate slots 28' Patented Feb. 2, 1965 terminals 4', and a pole piece 4 of an electromagnetic motor which includes a bellcrank armature 5, the vertically depending arm 5a of which pivotally overhangs the open end of the frame member and adjacent pole piece 4 from a knife-edge bearing 6 formed on the free end of upper arm 3, as shown in FIGURE 3.

Also mounted on arm 3 of the frame is an upwardly opening U-shaped bracket 8 formed of non-magnetic material having vertically extending wall portions 9 and 10, with its bottom wall portion 11 fixedly attached to arm 3 of the support by screws 12 or the like with the horizontally extending arms 5!) of the armature overlying wall portion 11. Projecting portions of frame arm 3 adjacent the ends of knife-edge bearing 6 are upset at 13 (FIGURE 2) to restrain the armature against lateral movement. A stud 14 extends through a hole 15 in the arm of the armature and is threadedly mounted in arm 3 of frame member I. A spring 16, the pressure of which is adjustable by means of a nut 17 on stud 14, yieldably holds the horizontal arm 5b of the armature 5 in Contact with wall 11 of bracket 3 thereby normally holding the vertical arm 5a of the armature spaced from the pole piece 4" of the electromagnet when the latter is deenergized.

As shown in FIGURE 2, armature arm 5b is reduced in width to provide bifurcations 18 between which a pawl 19 (FIGURE 3) is pivotally mounted on a shaft 20. A plate spring 21 at one end is riveted at 22 to arm 5b and the free end of the spring normally yieldingly holds the pawl against clockwise movement (FIGURE 3) about its shaft 20. A shaft 23 journaled in suitable bearings extends transversely between vertical wall portions 9, 10 and projects at 23' through and beyond wall 9 for a purpose to be later explained. Mounted midway between walls 9, ill; on the shaft 2-3 is a ratchet wheel 24, constructed of suitable insulating and wear resisting material, such as Nylasint, rigidly secured thereon by knurling, a press fit or the like. Ratchet wheel 24 is so positioned with respect to pawl 19 that ratchet engaging portion 19 of the pawl engages a tooth of the ratchet Wheel at a point lying above and at one side of a straight line passing through the centers of shafts 2d and 23. A flat ratchet-holding or stop spring 25 fastened at one end on mounting block 25, in turn fixedly attached to wall 11 of bracket 8, frictionally engages one of the ratchet wheel teeth at its opposite end. A stop abutment 2.7 on block 26 limits the vertically upward movement of pawl 19 and the rotation of ratchet wheel 24 and its shaft 23 in the direction of the arrow (FIGURE 3) each time the armature 5 is energized.

Adjustably mounted on the exterior of wall 9 of bracket 8 and in surrounding relation to the extension 23 of shaft 23, previously referred to, is a terminal block mounting member 28 of non-magnetic material held in adjusted in member 28 by means of screws 29. A circular, fiat, insulating, combined terminal and fixed contact supporting support member 30, comprised of Bakelite or similar material, is carried by and spaced from mounting plate member 28 by means of four or more bent arms 23:: thereon fixedly imbedded in contactor supporting block 30.

The extension 23 of ratchet shaft 23 projects through insulating block 3t and has fixedly mounted thereon, in close proximity to the outer face of circular insulating block 39, a cam member 31 composed of linen, Bakelite or the like, having a plurality of circumferentially equally or otherwise spaced, radially extending camming lugs 32 having fiat outer surfaces 32; the outwardly extending side walls of the lugs intersecting the outer flat surfaces 32 at an acute angle, up to degrees, to provide the lugs with sharp peripheral edges. Circular support member 39 has mounted thereon a plurality of shafts 33 saeaeae extending parallel to shaft extension 23', the shafts 33 being disposed in spaced relation to each other on a circle concentric to shaft extension 23. A greater number of shafts 33 are provided with respect to the number of camming lugs 32 on rotary cam 31. In the instant embodiment the cam 31 has six camming lugs 3... while eight shafts 33 are provided though up to twelve camming lugs (one half the number of teeth of the ratchet wheel) may be employed.

Disposed circumferentially and radially outwardly from shafts 33 are a plurality of terminal connection and fixed contact elements 34-, formed of brass or similar material, secured by rivets or the like onto the insulating circular supporting member 30. On each of shafts 33, as shown in FIGURES l and 5, is pivotally mounted a movable contact support member 35 having at one side thereof a cam-engageable contact actuator arm 35 integral therewith that extends inwardly toward rotary cam 31 in a plane parallel to the longitudinal axis of member 35, the free inner end of each arm 36 that is slidably engageable with cam lugs 32 being obliquely cut or beveled at 36 to form a sharp-edged, flat cam-lug engaging surface. While the cam-lug engaging surface of the arm 36 is in effect, for all practical purposes, sharp-edged the extreme innermost end edge thereof is in practice provided with a very minute radius to prevent it from scratching lugs 32 of the non-metallic cam member 31 and the term sharp-edged as applied thereto in the claims is to be so construed. Extending outwardly, substantially in alignment with arm 36, is an electrical contact arm 37. At the opposite side of pivoted contact support 35 is an outwardly extending abutment surface 38 parallel to arm 36 against which a return spring 39 bears. Groups of three of the terminal-contact elements 34-, designated respectively as 34a, 34b and 340 and as illustrated in FIGURES 1 and 5, are functionally related with each pivotally mounted contact support member 35. Return springs 39 for the pivoted contact support members 35, and which are each secured to a terminal 34a, also function as electrical conductors carrying current from the terminals 34a to the pivotally mounted contact support members 35 through a contact enlargement 39' at their inner ends. Terminals 34b and 340 each respectively have electrical contact elements 40 and 41, that control two circuits, disposed in facing relation to each other and between which is interposed a double or oppositely facing contact element 42 that is alternately engageable therewith and carried on the end of pivoted contact arm 37. The arcuate slots 28' in the insulator block supporting member ZS allow for slight arcuate adjustment of the initial position of the end 36 of contact actuator arm 36 relative to the camming lugs 32 of the rotary cam 31 when found necessary. Each terminal element 34a, 34b and 34c has a circular aperture 43 at its radially outer end providing a means whereby soldered electrical connections for the external circuits to be controlled may U be made.

In operation, assuming a source of current to be connected to each of terminals 34:: and each of terminals 34b and 34c of each terminal group are connected to various circuits to be controlled, the relay functions as follows. With reference to FIGURE 3, when the electromagnet 4 is energized through its terminals 4', armature 5 is thereby caused to oscillate on its knife edge bearing 6 since armature arm 5a is drawn toward pole-piece 4". Arm 5b of the armature pivots upwardly against the action of spring 16 causing pawl 19, which bears against a tooth of ratchet wheel 24, to move upwardly with it. Pawl 19 thereby rotates the ratchet wheel counterclockwise, as indicated by the arrow (FIGURE 3), against the yielding restraint of spring until the pawl strikes the stop abutment 27. The ratchet stop spring 25 then by its positive engagement of one of the teeth on ratchet wheel 24 prevents the pawl from reversely rotating the ratchet wheel as the armature is returned to its initial position under the influence of spring 16 when the electromagnet 4 is de-energized. During this return oscillation of the armature 5, the now held ratchet wheel 24 causes a small clockwise oscillation of pawl 1% against the action of fiat spring 21, permitting the pawl to ratchet over the teeth of the ratchet wheel so as not to interior with the return of the armature to its illustrated initial position.

As shaft 24 of ratchet wheel 25 oscillated counterclockwise in FIGURE 3, as just described, it caused a corresponding oscillation of cam 31, as viewed in FIG- URES l and 5, in a clockwise direction. As is apparent in these figures, as long as cam 31 rotates under repeated energization of electromagnet 4 at least one of the rotary cam engaging contact actuator arms 36 will be actu ted by one of the rotary cam lugs 32. slidably engaging its bevelled end 36'. This engagement instantaneously swings the pivoted contact support 35 counterclockwise in FIGURES 1 and 5 thereby swinging the movable contact 42 on arm 37 away from fixed contact 41 into engagement with fixed contact 4i Thus one circuit is opened while the other is closed. As cam 31 continues to rotate the fiat outer surface 32 of the cam lug 32, due to the pressure exerted by spring 39, will slidingly bear against the bevelled end 36 of contact actuating arm 36 until its sharp-edged end arrives at the sharp-edge of the cam lug. As the cam lug moves away from arm end 36 to release it the contact return spring 39, secured to current source terminal 34a, instantly thrusts rotary contact support 35 clockwise about its pivot 33 thereby snapping movable contact 42 away from fixed contact it and opening the circuit controlled thereby.

It is apparent that by reason of the difference in number of actuator arms 36 and cam lugs 32 a selective and a sequential engagement and disengagement of the various external circuits connected to contact terminals 345 and 34c will obtain. The functioning of the device with respect to one set of three terminal contacts will of course be repeated at all other sets. Since eight contact actuators 35 are used in the embodiment as illustrated it is obvious that twenty-four terminal units 34 are necessarily employed. However the device is not to be construed as limited to this number of elements; any desired number of related members may obviously be employed.

FIGURE 6 shows, as applied to the relay of FIGURES 1-5, a slightly modified electrical conductor connection etween the movable contact arm 37 and terminal 34a. A thin strap-like, flexible, U-shaped spring, conductor member 50, constructed of a copper alloy, is secured by soldering or the like at one of its ends to a contact arm 51 on terminal 34a abreast of the connection on the terminal of return spring arm 39, the opposite end 52 of the U-shaped member being connected, as by riveting or the like to the side of the end of movable contact arm 37 adjacent contact 40. The double contact 42 on arm 37 may comprise the double headed rivet that secures the end of the U-shaped conductor spring 50 to the lever. Member 5t") thus provides a position electrical connection between members 34a and 37 while at the same time it augments the snap spring action of member 39 in moving contact 42 on arm 37 from engagement with contact 40 on terminal 34b into engagement with contact 41 on terminal 34c. Thus, should member 39 fail to remain in effective electrical contact with support 35 for any reason whatsoever, it would not affect the operation of the relay to any noticeable extent.

FIGURE 7 illustrates another embodiment of the relay structure generally similar to that of FIGURES 1-5 but controlling three groups of single circuits, this particular number of course being purely a matter of arbitrary choice. In this form of the invention the U-shaped bracket 8', which supports the ratchet shaft 23 and the mounting member 28" for the circular insulating terminal and fixed contact-supporting member 3% of Bakelite or similar insulating material, is of a shape that provides for easier access to screws 29 for adjusting the initial setting of mounting member 28 and the circular support member 30 carried thereby. The ratchet shaft extends through member 30 and carries on its extension 23" a cam 31 in the same manner as in the first described construction, it being correspondingly provided with six equally spaced sharp-edged cam lugs 32'.

Angularly spaced around the face of the circular support member 30' in groups of two are mounted, by means of rivets or the like, a series of sets I, II, III of stationary terminal members 64a, 6412, the sets in the instant embodiment being three in number for control of three separate external circuits. Mounted on a circle intermediate the shaft extension 23" and each set of terminals on circular support member 30' are shafts 33, these shafts being each positioned concentrically of the shaft extension and in alignment with each group of terminals. As in the earlier embodiment, each shaft 33' pivotally mounts a movable contact support member 65.

Each contact support member 65, as clearly shown enlarged in FIGURE 8, is provided with an upper abutment means 65' against the lefthand edge of which thrusts a return spring 69 cantilevered from terminal 64a. The movable contact arm 67, which is of stepped configuration, is fixedly secured at 670, by means of solder or the like, to the support member 65 the radially outer free end portion 67a being offset at 67b in alignment with abutment element 65. An actuator arm 66 is dovetailed and solder connected to the innermost stepped portion 67d of contact member 67 and normal thereto for engagement by the lugs 32 of cam 31' as it rotates. The end of arm 66 is beveled to provide a sharp-edged carn engaging surface, the extreme innermost end edge, as in the first embodiment, being provided with a minute bevel to prevent scratching the cam lugs 32'.

Soldered or otherwise secured at 71 to terminal 64a, at the side opposite to the return spring 69 is connected a strap-like, flexible U-shaped spring conductor member 70, similar to member 50 in FIGURE 6, the conductor member 70 being riveted at 73 or otherwise connected to the outer end of portion 67a of the pivoted contact arm 67. The head of the rivet 73 forms an electrical contact adapted to engage with a stationary contact 74 on a projecting arm 75 of terminal 64b. The spring conductor 7% thus not only effects a positive electrical connection between terminal 64b and movable contact arm 67, it also acts in parallel with spring 69 to augment the snap action opening between contacts 73 and 74 when actuating arm 66 is released from engagement with ing 32' during rotation of cam 31' in the direction of the arrow in both FIGURES 7 and 3 to further aid in minimizing contact arcing. While spring 69 also acts as an electrical connection between terminal 64:: and the movable contact it is not primarily relied upon for this function in the present embodiment.

It is obvious that the U-shaped spring electrical conductor 70, in conjunction with spring 69, is equally effective for use in moving movable contact member 67 to a circuit closing as well as a circuit opening position. Thus, in FIGURE 7 at the terminal set III the terminals 64a, 64b are spaced wider apart to provide adequate room for the spring 70 to function, in conjunction with spring 69 to snap contact 73 on pivoted arm 67 into engagement with stationary contact 74 after release of actuating arm 66 by cam lug 32' during rotation of the cam 31'.

The relay of this invention is capable of extensive use in many different fields of application since it is capable of controlling circuits of relatively high amperage with the relay itself constructed of miniature proportions. It is extremely dependable in use by reason of its sturdy, compact and relatively simple construction.

It will be obvious to those skilled in the art that various changes may be made in the invention without departing from the spirit thereof and therefore, the invention is not to be considered as limited to the embodiment thereof as described in the specification and shown on the drawings, but only as indicated by the scope of the appended claims.

What is claimed is:

l. A relay mechanism comprising, in combination, motor means having an armature, a rotary cam having radially extending sharp-edged abutment means thereon, said rotary cam being rotatable by said motor means when energized, a plurality of electrical circuit-controlling terminal elements having fixed, spaced contact means thereon arcuately positioned and radially spaced outwardly of said rotary cam, contact means pivotally mounted intermediate said rotary cam and said arcuately positioned circuitcontrolling terminal elements and movable in a first direction by engagement with said sharp-edged cam-abutment means, spring means biasing said pivotally mounted contact means in the opposite direction, said pivotally mounted contact means being alternately engageable and disengageable with said fixed, spaced contact means of said circuitcontrolling terminals respectively by said sharp-edged cam-abutment means and said biasing spring means, said motor means comprising a supporting frame means having spaced parallelly extending arms, an electromagnet mounted between and in alignment with said frame arms, the pole end of said electromagnet being disposed adjacent one end of said frame arms, a knife-edged bearing formed on one of said frame arms at said one end thereof, a bellcranl: armature pivotally mounted on said bearing and having one of its arms disposed in cooperative relation to the pole end of said electromagnet, the ends of said one arm of said frame means being offset to prevent endwise displacement of said bellcrank armature, a U-shaped bracket having its bight portion rigidly secured on said one of said frame arms in the plane of said electromagnet and armature, the other arm of said bellcrank armature extending in overlying relation to said bight portion, and so constructed and arranged as to lie in engagement therewith when said electromagnet is de-energized, spring means engaging said other armature arm and mounted on said frame means intermediate said knife-edged bearing and said U-shaped bracket mounting and biasing said other armature arm into its bight engaging position, said other armature arm having a spring-biased detent thereon, a shaft mounted on said U-shaped bracket having a ratchet wheel secured thereon and rotatable by said detent means when said electromagnet is energized, said rotary cam being fixedly secured on a projection of said shaft.

2. A relay comprising a U-shaped frame support means, an electromagnet carried within said U-shaped frame support means, a bellcrank armature pivoted on the end of one of the arms of said U-shaped frame support means, spring means engaging said armature to bias it into position for operation by said electromagnet, pawl means carried by said armature, a rotary shaft carrying a ratchet Wheel being engaged by and rotated in one direction by said pawl, cam means fixed mounted on said shaft, a circular, flat insulating support means adjustably and fixedly mounted on said frame means in concentric relation to said cam means, spaced radially-extending sharp-edged camming lugs formed on the periphery of said cam means, a plurality of electrical terminals circumferentially mounted on one face of said circular insulating support means, a plurality of pivoted electrical contact support members circularly mounted in spaced relation on said one face of said circular insulating support means and radially intermediate said rotary cam means and said plurality of electrical terminals, the number of said pivoted electrical contact support members being different from the number of said cam lugs, each pivoted contact support member being operatively associated with a group of three terminals wherein two adjacent terminals of each group have external circuit-making contacts thereon in spaced facing relation, said pivoted contact support members each having oppositely extending aligned arms there greases on, one of said aligned arms comprising an electrical contact member extending between and engageable with either of said two facing contacts, the other of said aligned arms extending adjacent to said cam lugs, a U-shaped flexible spring electrical conductor member connected at one end on the third terminal of each said group and connected 7 described wherein an electro-magnetic motor acts through a pivoted pawl to rotate a ratchet wheel shaft, a frame mounting means, cam means fixedly mounted on said shaft, a flat, insulating support means arcuately adjustable and fixedly mounted on said frame means in concentric relation to said cam means, arcuately spaced radially extending sharp-edged camrning lugs formed on the periphery of said cam means, a plurality of groups of two terminal means circularly mounted in spaced circumferential relation on one face of said insulating support means, a plurality of pivoted electrical contact support members equal in number to said groups of terminals being concentrically mounted on said one face of said insulating support means, each of said pivoted contact support members being intermediate of said cam means and said terminal groups and operatively aligned with each of said terminal groups the number of said pivoted electrical contact support members being different from the number of said cam lugs, a contact lever means attached to and carried by each of said pivoted contact support members, a U-shaped, flexible spring electrical conductor member secured at one end thereof to one of said two terminals of each said group, the other end of said U-shaped, spring electrical conductor member being secured to the outer end portion of one of said pivoted contact lever means, said outer end portion of each said pivoted contact lever having an electrical contact thereon, the other of said two terminals of each said group having an electrical contact thereon disposed abreast in operative relation to said pivoted lever contact, an actuating arm attached to the inner end of each of said contact levers and having a beveled sharp-edged end surface thereon disposed in the rotary path of said cam lugs, whereby each pair of said terminal and pivoted lever contacts are alter nately engaged and disengaged by said U-shaped flexible spring member and said sharp-edged camming lugs on said cam means in an arc-minimizing manner.

4. A multiple contact relay mechanism as defined in claim 3 wherein an additional fiat spring means extends from said one of said two terminals of each said group and bears in biasing relation against said pivoted electrical support members to augment the action of said U-shaped flexible spring members, said securing means for the U- shaped spring conductor constituting said electrical contact means thereon.

References Cited in the file of this patent UNITED STATES PATENTS 1,378,945 Gilson et al May 24, 1921 2,928,916 Bonanno Mar. 15, 1960 2,957,966 Bennett Oct. 25, 1960 2,990,462 Dietz June 27, 1961 3,012,110 Price Dec. 5, 1961 

1. A RELAY MECHANISM COMPRISING, IN COMBINATION, MOTOR MEANS HAVING AN ARMATURE, A ROTARY CAM HAVING RADIALLY EXTENDING SHARP-EDGED ABUTMENT MEANS THEREON, SAID ROTARY CAM BEING ROTATABLE BY SAID MOTOR MEANS WHEN ENERGIZED, A PLURALITY OF ELECTRICAL CIRCUIT-CONTROLLING TERMINAL ELEMENTS HAVING FIXED, SPACED CONTACT MEANS THEREON ARCUATELY POSITIONED AND RADIALLY SPACED OUTWARDLY OF SAID ROTARY CAM, CONTACT MEANS PIVOTALLY MOUNTED INTERMEDIATE SAID ROTARY CAM AND SAID ARCUATELY POSITIONED CIRCUITCONTROLLING TERMINAL ELEMENTS AND MOVABLE IN A FIRST DIRECTION BY ENGAGEMENT WITH SAID SHARP-EDGED CAM-ABUTMENT MEANS, SPRING MEANS BIASING SAID PIVOTALLY MOUNTED CONTACT MEANS IN THE OPPOSITE DIRECTION, SAID PIVTOALLY MOUNTED CONTACT MEANS BEING ALTERNATELY ENGAGEABLE AND DISENGAGEABLE WITH SAID FIXED, SPACED CONTACT MEANS OF SAID CIRCUITCONTROLLING TERMINALS RESPECTIVELY BY SAID SHARP-EDGED CAM-ABUTMENT MEANS AND SAID BIASING SPRING MEANS, SAID MOTOR MEANS COMPRISING A SUPPORTING FRAME MEANS HAVING SPACED PARALLELY EXTENDING ARMS, AN ELECTROMAGNET MOUNTED BETWEEN AND IN ALIGNMENT WITH SAID FRAME ARMS, THE POLE END OF SAID ELECTROMAGNET BEING DISPOSED ADJACENT ONE END OF SAID FRAME ARMS, A KNIFE-EDGED BEARING FORMED ON ONE OF SAID FRAME ARMS AT SAID ONE END THEREOF, A BELLCRANK ARMATURE PIVOTALLY MOUNTED ON SAID BEARING AND HAVING ONE OF ITS ARMS DISPOSED IN COOPERATIVE REALTION TO 